Optimisation of microwave-assisted encapsulation of black mulberry (morus nigra) extract

Abstract

Black mulberry (Morus nigra) fruit extract contains high amounts of a bioactive compound known as anthocyanin. However, this compound is very sensitive to heat and light. Encapsulation is the most efficient method to protect the anthocyanin from harsh environments. In this study, a combination of gum Arabic and maltodextrin was used as wall materials to encapsulate black mulberry extract using a microwave-assisted technique. The main objective of this study was to optimise the microwave-assisted encapsulation of black mulberry to achieve an extract with the highest encapsulation efficiency (EE), total anthocyanin content (TAC), and antioxidant capacity (DPPH inhibition). The factors studied were material core-to-wall ratio (1:3-1:10), microwave power (450-630 W), and encapsulation time (2-4 min). The experiment followed a Face-Centred Central Composite Design. Based on the ANOVA results, only the core-to-wall ratio had a significant effect on EE, TAC, and DPPH while power only had a significant effect on DPPH. Based on the desirability function, the optimum encapsulation of black mulberry extract was 90.14 % EE, 23.03 mg/g dry basis TAC, and 85.37 % DPPH inhibition, obtained using the following microwave-assisted encapsulation parameters: core-to-wall ratio of 0.19 mL/mL, microwave power of 450 W, and time of 2.94 min.